Artificial silk filament



names May 1,1935

UNITED. STATES PATENT mm:

: James A. Singmaster, Bronxville, Y.

No Drawing. ApplicationJune 29, 1929, 7 Serial No. 374,968

4 Claims.

My invention relates to the manufacture of artificial silk filaments andhas for its object to provide a filament which shall be characterized bya desirable opacity, covering power and lustre and shall also preferablyhave a desirable softness of texture. In my application filed Senatember 28, 1927, Serial Number 222,685, (which has since issued intoUnited States Patent 1,725,- 742, August 20, me). I have described andclaimed broadly the method of producing a filament of improved opacityand covering power and the filament having these qualities, the proc--ess consisting broadly speaking in incorporating with the solution to bespun into a filament by forcing it through a small orifice, distributedparticles of inorganic pigment-like material of small area as comparedwith that of the orifice through which the solution is forced to formthev filament and so used as to quantity and distribution as not toimpair the continuity of the mass material of the filament. This processis described and claimed in greater elaboration and with variouslimitations my supplemental application filed May 8, 1929,- SerialNumber361,543, (which has since issued into United Stat Patent 1,875,- 894,September 6, 1932), in whic application I have pointed out in moredetail the necessary qualities of inorganic pigment-like material usablewith advantage in my process and the filament resulting therefrom and Ihave also demribed what I believe to be the best method forincorporating and distributing inorganic pigment particles in thesolution of the cellulose compound which is to be spun into filaments,point-- ing out as the best method known to be a thorough admixture ofthe inorganic pigment particles with the solvent prior to its admixturewith the soluble cellulose compound so that in the wetting of thiscompound by the solvent and the process of dissolving the compound inthe solvent the pigment particles will be thoroughly distributedthroughout the resulting solution and also pointing out that thisdistribution is further facilitated and made more complete by passingthe solution through the filtering system, which is always employed-tofree the cel-'- lulose solution from such particles as would tend toclog the orifice or to impair the continuity of the mass of thefilament. m this supplemental application I have included a schedule ofwhat I believe to be the best inorganic pigment-like materials usable inmy process, pointing out 'as an important qualification that the pigmentparticles shall not materially exceed .75 microns in size; that theyshould be of such a character that their light refractive index differsfrom that of the mass material of the filament in which they areembodied and that for the best results the pigment particles should besubstantially white in color and I have specified with regard to thescheduled pigments the relative proportions in which they should be usedto produce substantially similar results as to opacity, covering powerand lustre in the ifinished'filament and I- have specifically claimed'inthat application 1 the use of titanium oxides in view of the fact that Ihave found these oxides to give the best results. In my applicationfiled May 18, 1929, Serial Number 364,342, I have described my furtherinvention of a method of manufacturin an improved filament and of thefilament so produced in which'in addition to incorporating I inorganicpigment particles as above described in the solution and the filament!also incorporate in the filament small particles of an oil or anoleaginous material of such size and distribution that they do notmaterially impair the continuity and strength of themass' material ofthe produced filament and the presence of which in the filament I havefound to lead to. im-

proved results both in the ap earance ofthe filament and in its texture;and I have further described in this application as the best method ofobtaining the proper particle size and distribution of the oil that theoil be of such a character that it is soluble in the solvent of thesoluble cellulose compound or in a solvent non-reactive with thechemicals employed in the manufacture of the solution so that employedshould it will remain in solution in the solution of the cellulosecompound and be precipitated in the filament after its formationas thesolvent is eliminated therefrom. I

The object of my present application is to cover specifically in theprocess and the produced filament above described the use of zirconiumoxide,-

ZlOz, which inorganic pigment-like material I have found to beadvantageously usable both in the described methods and in the resultantprodnets and the protection sought by this application application tospecifically claim and protect the use of zirconium oxide in thedescribed way, I

having discovered that it is suitable for use by reason of its particlesize which may be stated as, when properly prepared, of about 2 micronsby reason of the fact that it can be used in sufiicient quantity toobtain a desirable opacity and covering power in the filament withoutmaterially impairing the continuity of the mass material of thefilament, highly desirable opacity and covering power being obtainableby the use of this pigment when used in the proportions of 4 percent byweight to the weight of the solution of cellulose compound with which itis admixed. By reason however of the fact which I have discovered thatthe soluble cellulose compoundcontaining the distributed particles ofzirconium oxide can be subjected to the usual thorough filteringoperation without the elimination of the said particles from thesolution and by reason of the fact that when the oil solution is mixedwith the solution of the cellulose compound in addition to the particlesof zirconium oxide the oil will be precipitated in the filament in aseparate system of distributed. particles to the system of distributedparticles of zirconium oxide.

I may note as a further discovery that in cases in which a finelydivided oil or oleaginous ma: terial adapted to act as a softener ismixed with the solution of the cellulose compound without beingdissolved therein that'the zirconium oxide also mixed with the solutionwill be maintained in a separate system of distributed particles andwill be found in the filament prepared from such a solution also in aseparate system of distributed particles from the system of distributedparticles of oleaginous material. This is an important fact when thezirconium oxide particles are incorporated in the solution used in themanufacture of viscose and cupra ammonium silks in which processes itwill be found most advantageous to mix the oleaginous material in thesolution in a filament. state of finely distributed particles not insolution. a

In the case of nitrocellulose solutions and solutions of celluloseacetate it is decidedly advantageous to bring and maintain the oil in astate of solution until'the filament is formed.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. An artificial silk filament oi diminished luster having submerged inand distributed throughout its mass material fine particles of preformedzirconium oxide substantially white in .color and having a lightrefractive index substantially diiferent from that of the mass material,the size of said particles not materially exceeding 0.75 microns andsaid particles being present in such small quantity and so thoroughlydispersed in the mass material as notto materially impair the continuityof such mass material.

2. An artificial silk filament having immersed in and thoroughlydispersed in its mass material fine particles of zirconium oxide, thequantity and dispersion of such particles being such as not tomaterially impair the continuity and strength of the'mass material ofthe filament, said filament having also distributed through its massfineparticles of oleaginous material of such size and thoroughdistribution as not to materially impair the continuity and strength ofthe mass material of the filament, said oleaginous material beingpresent-in amount adapted to soften the filaments.

3. An artificial silk filament of diminished lustre having submerged in,and thoroughly distributed throughout its mass material fine part clesof zirconium axide pigment, the zirconium oxide pigment being present insuch an amount as not materially to impair the continuity and strengthof the mass material of the filament.

4. An artificial silk filament according to the preceding claim, inwhich the zirconium oxide pigment is present amount not exceeding about4% by weight of the mass of the finished ,JAME'S A.- smamsraa.

